Vibration energy harvesting technologies are developing rapidly, showing great potential in many different applications. For example, miniature vibration energy harvesters are often used for applications such as autonomous sensors and system on chip applications. Most applications use one of four major vibration energy harvesting mechanisms, including electromagnetic, electrostatic, magnetoelastic, and piezoelectric mechanisms. However, such vibration energy harvesters achieve different output powers and energy densities. For example, piezoelectric-based vibration energy harvesters often demonstrate a much higher energy density than other counterpart mechanisms, reaching ˜6 mW/cm3. Specifically, some piezoelectric bare beam based vibration energy harvesters can generate a power of 6.63 mW/cm3. Because of this, piezoelectric-based vibration energy harvesters are often more widely used than other forms of vibration energy harvesters. However, they can suffer from narrow bandwidth (or a limited operating frequency range of 2-5% of the center operating frequency), degraded polarization after prolonged use, and/or the negative side-effects caused by a brittle cantilever.